Organopolysiloxane compositions which form transparent mixtures when diluted with water are described in European Patent Application No. 0 068 671 to Dow Corning Limited. These compositions contain a salt of a water-soluble organic or inorganic acid and an organopolysiloxane, which in addition to the other siloxane units, also contains siloxane units containing SiC-bonded radicals having basic nitrogen atoms, methyltrimethoxysilane, a silicon compound which is soluble in such a salt and a water-soluble solvent.
Also, U.S. Pat. No. 4,661,551 to Mayer et al describes an aqueous transparent composition containing (A) a salt of a water-soluble organic or inorganic acid and a polysiloxane in which the polysiloxane contains, in addition to other siloxane units, siloxane units containing monovalent SiC-bonded radicals having basic nitrogen in an amount of at least 0.5 percent by weight of basic nitrogen, based on the weight of the polysiloxane; (B) an organosilicon compound containing basic nitrogen in an amount of from 0 to 0.5 percent by weight, based on the weight of the organic silicon compound, and when constituent (B) is present in an amount less than 0.1 part by weight per part by weight of constituent (A), then constituent (B) contains at least one organic silicon compound having a molecular weight which does not exceed 600 g per mol and (C) an organic solvent including octanols which may be present in an amount up to about 5, percent by weight based on the weight of constituent (A), in which the organic solvent is soluble in water up to and including one part by weight per 100 parts by weight of water at 20.degree. C. and 1020 hPa (absolute) and is free of halogen atoms.
The organosilicon compound (B) may consist of an organopolysiloxane containing aliphatic radicals which are bonded to silicon via oxygen and which have a molecular weight of approximately 600 g per mol.
Therefore, it is an object of the present invention to provide organopolysiloxane emulsions which form transparent compositions when diluted with water. Another object of the present invention is to provide aqueous organopolysiloxane emulsions containing aliphatic radicals that are bonded to silicon via oxygen and which have a molecular weight of at least 620 g per mol and which may be free of an organic solvent which is water-soluble up to and including one part by weight per 100 parts by weight of water at 20.degree. C. and at 1020 hPa (absolute), and is free of halogen atoms. Still another object of the present invention is to provide an aqueous organopolysiloxane emulsion which has a very long shelf life without any sign of demulsification, when used as an impregnating agent. A further object of the present invention is to provide aqueous organopolysiloxane emulsions which are highly compatible with other resins. A still further object of the present invention is to provide aqueous organopolysiloxane emulsions which have adequate crosslinking and form clear, highly water-resistant films.